This is very similar to the situation in my apartment. There may be a disgusting mountain of cat vomit on the floor when I wake up in the morning. It very well may not be there anymore when I get home. It’s magic, and it has a name: Balin!
So, while I do have a cat with a water fixation (Balin), I’m very glad that he hasn’t figured out how to do this. Check out this video.
(please ignore the “View this video on Google” link for now - I’ll get that part of my video embed plugin working later)
I pity their water bill.